Superconducting gap of overdoped Tl2Ba2CuO6+d observed by Raman scattering

TL;DR

This study uses Raman scattering to investigate the superconducting gap in overdoped Tl2Ba2CuO6+d, revealing s-wave component mixing into the d-wave gap, a phenomenon also seen in other high-Tc superconductors.

Contribution

It provides experimental evidence of s-wave component mixing in the superconducting gap of overdoped cuprates using Raman spectroscopy.

Findings

Pair-breaking peaks shift to lower energy with doping

S-wave component mixing observed despite tetragonal structure

S-wave mixing appears common in overdoped high-Tc superconductors

Abstract

We report Raman scattering spectra for single crystals of overdoped Tl2Ba2CuO6+d (Tl-2201) at low temperatures. It was observed that the pair-breaking peaks in A1g and B1g spectra radically shift to lower energy with carrier doping. We interpret it as s-wave component mixing into d-wave, although the crystal structure is tetragonal. Since similar phenomena were observed also in YBa2Cu3Oy and Bi2Sr2CaCu2Oz, we conclude that s-wave mixing is a common property for overdoped high-Tc superconductors.